The basic objective of the proposed research is to provide a better understanding of the developmental process germination in the yeast Saccharomyces cerevisiae. Germination is an excellent model to study eukaryotic cell differentiation since the concomitant biochemical events to convert a eukaryotic cell from a largely inactive metabolic state to an active one can be thoroughly investigated. By comprehending the biochemical mechanisms which govern yeast germination, this may stimulate the development of germination-specific inhibitors. Such inhibitors could prove relevant to the clinical study of pathogenic yeast species. The proposed experiments should generate substantial information regarding the biochemistry of S. cerevisiae ascospore germination. The primary goal of this project will be to isolate germination-deficient yeast strains. To this end, a homothallic strain and a heterothallic strain of yeast will be utilized as the parent diploid strains. A protocol has been devised that should allow the selection of mutants defective for ascospore germination. With the isolation of possible mutants, individual mutant strains will be screened to determine when the morphological and spectrophotometric changes associated with germinating yeast ascospores arrest. The possibility that germination is blocked in these mutants due to a problem in ascosporogenesis will be investigated. The ability of these mutants to utilize selected carbon sources will be examined to judge if their vegetative growth on these compounds has been blocked by mutation. Protein synthesis during germination will be measured for each mutant during specific time intervals so that the effect of the respective mutation affecting yeast germination on protein synthesis can be evaluated. Lastly, two-dimensional polyacrylamide gel electrophoretic analysis will be performed to corroborate the protein synthesis data and to provide more specific information about the nature of the proteins being synthesized in the germination mutant strains.